Method of making a countersunk riveted joint



April 11, 1967 D. F. LEONHART METHOD OF MAKING A COUNTERSUNK RIVETEDJOINT 2 Sheets-Sheet 1 Filed Aug. 31, 1964 FIG. I

INVENTOR. DONALD E LEONHART FIG. 2

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ATTORNEYS April 11, 1967 D. F. LEONHART fi METHOD OF MAKING ACOUNTERSUNK RIVETED JOINT Filed Aug. 31, 1964 2 Sheets-Sheet 2 1/ All]!My FIG. 3

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INVENTOR. DONALD E LEONHART ATTORNEYS United States Patent 3,313,022METHOD OF MAKING A COUNTERSUNK RIVETED JOINT Donald F. Leonhart,Youngstown, Ohio, assignor to The Youngstown Steel Door Company,Cleveland, Ohio Filed Aug. 31, 1964, Ser. No. 393,313 7 Claims. (Cl.29-509) This invention relates to riveting, and more particularly to anovel method for flush riveting sheet metal members.

On many single sheathed plug door applications, it is essential that thedoor have a smooth inside surface. Any protrusions, such as raised rivetheads or other obstructions, cannot be tolerated. Smooth surfaces areessential to eliminate the possibility and hazard of damage to productsused in association with the riveted surfaces. For example, it isnecessary to have a smooth Working surface when loading and unloadingrolls of newsprint. If these rolls were allowed to strike or in someother way come into sharp contact with raised projections such as rivetheads, the newsprint would become damaged, resulting in great waste. I

Smooth surfaces obtained by riveting means have been achieved in thepast. However, these have been achieved With a number of limitations orspecial, costly requirements. For instance, smooth, riveted surfaceshave been obtained where the metallic sheet members were very thin. Inother instances, the use of special alloys was necessary to produce therequired, smooth, riveted surface. In other cases, special pre-rivetingmachining operations such as countersinking were needed. Still in othercases the use of special rivets was required. These prior methods haveall been inefficient and expensive because of the need for specialmachining operations and special alloys or rivets to produce rivetingoperation yielding acceptable results.

The novelty of this invention is that it provides a method that requiresno special machining operations before riveting. Also the new rivetingoperation does not require specially designed rivets. In addition, nospecial deformation of the rivet is required before the actual rivetingoperation to achieve a smooth, flush surface on one side of the rivetedassembly. Furthermore, no special alloys are necessary, as this novelriveting method uses standard rivets. Finally, this novel rivetingoperation requires smaller pressing forces because only one metal sheetis deformed in the riveting process insteadof two or more sheets havingto be deformed as in previous countersunk riveting operations.

Thus, the object of this invention is to provide a simple, economicalmethod for countersinking rivets in substantially heavy gauge metals.

A further object of this invention is to provide a method for drivingand countersinking rivets in one continuous uninterrupted pressingoperation, requiring no special alloys.

A further object of this invention is to provide a method for drivingand countersinking rivets that are standard, not special items.

A further object of this invention is to provide a method for drivingand countersinking rivets in one pressing operation not requiringpreparatory pre-machining, preforming, or pre-deforming operationsbefore the actual riveting.

Further objects and advantages will become apparent from the followingspecification and claims and examination of the drawings.

FIG. 1 is a fragmentary view of a single sheathed plug door made ofsheets of metal riveted together.

FIG. 2 is a partial cross sectional view on line 2-2 3,313,022 PatentedApr. 11, 1967 of FIG. 1 showing in part the riveted construction of asingle sheathed plug door.

FIG. 3 is an exploded view of three fragmentary sheets of metal and therivet that is to hold them together.

FIG. 4 shows the three sheets of metal and rivet in juxtaposition priorto the riveting operation.

FIG. 5 is a fragmentary sectional view of three metal sheets after theflush riveting operation is completed.

FIG. 6 is an exploded view of two fragmentary sheets of metal and therivet that is to hold them together.

FIG. 7 shows the two sheets of metal and rivet in juxtaposition prior tothe riveting operation.

FIG. 8 is a fragmentary sectional view of the two metal sheets after theflush riveting operation is completed.

Referring to the drawings, and particularly FIG. 3, members 10, 12 and14 represent three metal sheets to be riveted together. The aperture 16in member 12 is materially larger than apertures 18 and 20 in members 10and 14 respectively.

The clearance between the diameters of apertures 18 and 20 and thediameters of rivet shank 22, FIG. 4, is only large enough to allow shank22 to slide through apertures 18 and 20 freely and without interference.However, aperture 16 is materially larger than apertures 18 and 20 sothat when members 10, 12 and 14 are in juxtaposition and apertures 16,18 and 20 are generally concentric, some metal in members 10 and 14overlaps aperture 16 in member 12. While aperture 16 is materiallylarger than apertures 18 and 20, aperture 16 is however, substantiallysmaller than the diameter of the head 28 of rivet 24. Rivet 24 is a fiathead rivet requiring no special machining or shaping.

The apertures 18 and 20 in sheets 10 and 14, respectively, can be formedby punching, drilling or by any conventional, feasible or practicalmanufacturing means. These apertures have parallel walls and requireneither special machining operations nor must they be held to unusuallyclose tolerances.

During a riveting operation, a compressing force is applied against theend 26 of rivet 24, FIG. 4, while the rivet head 28 is held stationary.The entire riveting operation is done in one, continuous, uninterruptedopera tion.

As an axial force is applied against the rivet end 26, the shank 22begins to be upset and expands. As the shank expands, its lengthdecreases while its diameter increases slightly and contacts the metalon the inside of aperture 18 in member 10.

As rivet shank 22 continues to be compressed, it continues to expand,and the metal in the shank tends to ex- .pand in an outward and upwarddirection as shown in FIG. 5. The expanding metal in shank 22 forcessome of the metal in member 10 that is overlapping aperture 16 toextrude upward into and occupy part of aperture 16.

As the shank 22 extrudes the metal in member 10 and displaces it upward,a void space is formed in member 10 in the vicinity of aperture 18. Asthe upsetting of the rivet shank 22 continues, the swaged metal of theshank 22 occupies the space it has created in member 10. A portion ofthe deformed shank also occupies part of aperture 16 in member 12.

When the riveting operation is complete, FIG. 5, the rivet iscountersunk, and rivet end 26 is flush with the outer surface of member10. Shank 22 is deformed, having pushed into aperture 16 a portion ofthe metal in member 10 that was overlapping aperture 16 and havingfurther occupied the space that was created when that part of ember 10was swaged into aperture 16.

. Sheets 10, 12 and 14 are now securely locked together, the rivet end26 being flush with the outer surface of member 10 which olfers acontinuous, smooth surface.

Referring now to FIG. 6, members 30 and 32 represent two sheets of metalto be riveted together, having apertures 36 and 34, respectively.

Aperture 36 is only large enough to allow shank 38 of rivet 40, FIG. 7,to slide through it freely and without interference. than aperture 36 sothat when sheets 30 and 32 are in juxtaposition and apertures 34 and 36are generally concentric, some metal in sheet 30 overlaps aperture 34 insheet 32. Although aperture 34 is materially larger than aperture 36, itis nevertheless substantially smaller than the diameter of the head 39of rivet 40. Rivet 40 is a flat head rivet requiring no specialmachining or shaping.

The apertures 34 and 36 can be formed by punching, drilling or by anyconventional, feasible, or practical manufacturing method. Theseapertures require neither special machining operations nor must they beheld to unusually close tolerances.

During a riveting operation, a compressing force is applied against theend 42 of rivet 40 while the rivet head 39 is held stationary. Theentire riveting operation is done in one, single, continuous,uninterrupted process.

As force is applied against rivet end 42, the shank 38 begins tocompress and expand. As the shank expands, its length decreases whileits diameter increases slightly and first makes contact with the metalon the inside of aperture 36 in sheet 30.

As rivet shank 38 continues to be compressed, it continues to expand,and the metal in the shank tends to flow in an upward direction as shownin FIG. 8. The expanding metal in shank 38 forces some of the metal insheet 30 that is overlapping aperture 34 to extrude upward into andoccupy part of the space of aperture 34.

As the shank 38 extrudes the metal in member 30 and displaces it upward,a substantially conical space is formed in member 30. As the upsettingof rivet shank 38 continues, the flowing metal of the shank 38 occupiesthe space it has created in sheet 30. A portion of the deformed shankalso occupies a portion of aperture 34 in sheet 32.

When the riveting operation is completed, FIG. 8, the

rivet is countersunk and rivet end 42 is flush with the.

outer surface of sheet 30. Shank 38 is deformed, having pushed intoaperture 34 that portion of metal in sheet 30 that was overlappingaperture 34 and having further 7 occupied the space that was createdwhen a part of sheet 30 was extruded into aperture 34. Sheets 30 and 32are now securely locked together, the rivet end 42 being perfectlysmooth and flush with the upper surface of sheet 30.

For ease of description, the principles of the invention have been setforth in connection with several illustrated embodiments showing acountersunk riveting operation. It is not the applicants intention thatthe illustrated embodiments nor the terminology employed in describingthem be limiting inasmuch as variations in these may be made withoutdeparting from the spirit of the invention. Rather, applicant desires tobe restricted only by the scope of the appended claims.

The invention claimed is:

1. A method of riveting a plurality of metal sheets having large andsmall apertures therein which consists of inserting through saidapertures a rivet having a head, a shank, and an end portion with thehead being adjacent to one side of the sheets and the shank extendingthrough the sheets, the sheet with the larger aperture therein be-However, aperture 34 is materially largering between the outer sheet andthe head of the rivet, holding said rivet head axially immobile andapplying suflicient axial force against the end of the rivet shank toupset said rivet shank, compressing said shank so it expands and deformsthe metal sheet nearest the rivet end, and displaces a portion of saidsheet into the larger rivet aperture of the adjacent metal sheet, therivet shank being further compressed and shortened, and assuming asubstantially bulbous shape and occupying the space created by thedeformed metal sheet, the rivet shank being still further compresseduntil the end of said rivet shank is flush with the outer surface of thesheet nearest the rivet end, the entire riveting operation being done inone, continuous, uninterrupted process.

2. A method of riveting a plurality of metal sheets as defined in claim1 in which there are at least two metal sheets. 7

3. A method of riveting a plurality of metal sheets as defined in claim1 in which there are at least three metal sheets.

4. A method of riveting a plurality of metal sheets as defined in claim1 in which the walls of the rivet aperture are substantiallyperpendicular with the surfaces of the metal sheets being riveted.

5. A method of riveting a plurality of metal sheets as defined in claim1 in which the metal surrounding the. rivet aperture is deformed as partof the continuous, uninterrupted riveting operation.

6. A method of riveting a plurality of metal sheets as defined in claim1 in which the rivets are flat head type rivets.

7. A method of riveting a plurality of metal sheets having differentsize apertures therein, which consists of inserting through saidapertures a rivet having a head, a shank, and an end portion, one ofsaid sheets being an outer sheet and adjacent to the said end portion,another of said sheets being next adjacent towards said head from saidend portion, said latter sheet having a larger aperture than said outersheet, holding said rivet head axially immobile and applying sufficientaxial force against the end of the rivet shank to upset said rivetshank, compressing said shank so it expands and deforms the metal sheetnearest the rivet end, and displaces a portion of said sheet into thelarger rivet aperture of the adjacent metal sheet, the rivet shank,being further compressed and shortened, and assuming a substantiallybulbous shape and occupying the space created by the deformed-metalsheet, the rivet shank being still further compressed until the end ofsaid rivet shank is flush with the outer surface of the sheet nearestthe rivet end, the entire riveting operation being done in one,continuous, uninterrupted process.

References Cited by the Examiner UNITED STATES PATENTS 789,107 5/1905Steele 287l89.36 X 1,861,814 6/1932 Peters. 1,986,981 1/1935 Ross.2,047,341 7/1936 Vaughn et al. 29509 2,323,814 7/ 1943 Lamb et a1.29243.53 2,395,348 2/1946 Sherman et al. 29509 2,991,858 7/1961 Tayloret al. 37 X FOREIGN PATENTS 1,141,545 9/1957 France.

CHARLIE T. MOON, Primary-Examiner,

1. A METHOD OF RIVETING A PLURALITY OF METAL SHEETS HAVING LARGE ANDSMALL APERTURES THEREIN WHICH CONSISTS OF INSERTING THROUGH SAIDAPERTURES A RIVET HAVING A HEAD, A SHANK, AND AN END PORTION WITH THEHEAD BEING ADJACENT TO ONE SIDE OF THE SHEETS AND THE SHANK EXTENDINGTHROUGH THE SHEETS, THE SHEET WITH THE LARGER APERTURE THEREIN BEINGBETWEEN THE OUTER SHEET AND THE HEAD OF THE RIVET, HOLDING SAID RIVETHEAD AXIALLY IMMOBILE AND APPLYING SUFFICIENT AXIAL FORCE AGAINST THEEND OF THE RIVET SHANK TO UPSET SAID RIVET SHANK, COMPRESSING SAID SHANKSO IT EXPANDS AND DEFORMS THE METAL SHEET NEAREST THE RIVET END, ANDDISPLACES A PORTION OF SAID SHEET INTO THE LARGER RIVET APERTURE OF THEADJACENT METAL SHEET, THE RIVET SHANK BEING FURTHER COMPRESSED ANDSHORTENED, AND ASSUMING A SUBSTANTIALLY BULBOUS SHAPE AND OCCUPYING THESPACE